Within a sewage pipe buried under the ground, sediment, sludge and foreign matter may be accumulated by use for a long period. Therefore, it becomes necessary to remove the accumulated sediment, sludge and foreign matter and clean the sewage pipe.
Further, since the sewage pipe buried under the ground may be deteriorated as time goes, clacks and failures of joint portions and so forth can be caused. Particularly, when the sewage pipe is Hume pipe, a hole can be formed by corrosion. Accordingly, it becomes necessary to perform an inspection of the inside of the sewage pipe and to regularly perform a maintenance and an exchange.
As set forth above, upon performing a working of cleaning, inspection, maintenance, exchange and so forth of the sewage pipe, it has to be necessary to interrupt use of the sewage system during a working period since an equipment has to be inserted within the sewage pipe in the working zone or a worker has to enter the sewage pipe for working.
As a solution for the foregoing problem, a sewage by-pass drainage system for sewage pipe works disclosed in Japanese Examined Utility Model Publication (Kokoku) No. Heisei 6-13890, for example, has been known.
As shown in FIG. 5, the foregoing sewage by-pass drainage system for sewage pipe works 1 defines a working zone for a portion 1a between a first manhole 2 and a second manhole 3 of the sewage pipe 1, and provides stop plugs 4 at a portion 1b of upstream side and a portion 1c of downstream side of the sewage pipe 1a as the working zone so that the sewage or so forth may not flow in the sewage pipe 1a of the working zone.
Then, a suction pipe 6 of the pump 5 arranged on the ground is arranged at the portion 1b of the upstream side and a discharge pipe 7 of the pump 5 is arranged at the portion 1c of the downstream side so that the sewage or so forth at the upstream side of the working zone flows to the downstream side by-passing the working zone.
By the sewage by-pass drainage system for sewage pipe works as set forth above, the sewage or so forth may not flow through the sewage pipe of the working zone while the sewage system is used. Therefore, a working of cleaning, inspection, maintenance, exchange or so forth of the sewage pipe of the working zone, can be done with using the sewage system.
However, in the sewage by-pass drainage system for sewage pipe works as set forth above, by means of the pump 5 installed on the ground, the sewage or so forth within the sewage pipe is sucked. Since a pump head H required for the pump 5 is large, the sewage in the sewage pipe cannot be sucked sufficiently.
Particularly, since the burying depth of the main pipe of the sewage pipe is deep, the pump head required for the pump 5 is significantly large to make it impossible to suck the sewage or so forth in the sewage pipe.
Further, a screen 8 is provided on the ground so as to avoid a penetration of foreign matter in the sewage or so forth into the pump. Since such screen 8 tends to be stuffed, it has to be regularly cleaned and exchanged. However, on the ground, upon cleaning and exchanging of the screen 8, the sewage or so forth can flow out to cause a leakage of odor to the environment to be undesirable in view point of the environment protection.
Therefore, it is an object of the present invention to provide a sewage by-pass drainage system for sewage pipe works so that sewage or so forth can be drained even for the deeply buried sewage pipe and an odor may not leak on the ground.